The Civil War and U.S. Empire transformed U.S. relationships among race, law, and constitutionalism in the late-19th and early-20th centuries. Traditional accounts portray these events as iterative, with Republicans and the Supreme Court abandoning ideals of Reconstruction just in time for the United States – through annexation from Spain of Puerto Rico, Guam, and the Philippines – to take a deliberate imperial turn in 1898-1899. That account is wrong. As recent scholarship has anticipated, debates over meanings of the Civil War, the early postbellum period, and the Reconstruction Amendments to the Constitution raged on into the 20th century. Puerto Rican leaders perceived the dynamic. Across 1898-1917, they sought traction with U.S. officials by asserting that political and constitutional issues arising from U.S. empire were best understood with reference to the Civil War and its aftermath. Close study of their efforts illuminates that legal legacies of Reconstruction, which initially formed potential limits on colonial governance, were eventually dismantled by the judges and elected officials who oversaw U.S. empire. In particular, before annexation of Puerto Rico – but not two decades later – it was reasonable to argue that the Constitution as modified by the 14th and 15th Amendments made all non-tribal U.S. peoples into (1) U.S. citizens with substantive privileges and immunities that included access to the franchise on the same terms as whites and (2) citizens of a state or of a territory on the road to statehood. In line with that shift, numerous prominent U.S. jurists in 1898 and not in 1917 asserted that annexation automatically brought U.S. citizenship, eventual statehood, and full constitutional protections all in a bundle. Hoping to benefit from the shift away from the ideals of Reconstruction, leading Puerto Rican politicians came to embrace white-supremacist mischaracterizations of that history as a tragic instance of northern tyranny. Asserting that those ostensible postbellum errors were being reprised in Puerto Rico, these island leaders argued – with mixed results – that Puerto Rico too required “Redemption” into home rule.